This invention relates to a support structure for a resonant system.
It is known to use a resonant system for force amplification. The resonant mode in which a resonant system vibrates depends upon where it is constrained, the frequency of vibrations applied thereto, and its geometry. For example, a straight beam unconstrained at its ends has a fundamental free-free resonant mode in which anti-nodes are formed at the respective ends of the beam and a pair of spaced apart nodes are formed between the ends of the beam. The beam is supported and at least partially constrained at the nodes. Vibrations near the resonant frequency are applied to one end, which serves as the input to the resonant system, and the other end of the beam, which serves as the output of the resonant system, is coupled to a work object--either directly or by means of a tool. Typical examples of such resonant systems are disclosed in Bodine U.S. Pat. Nos. 3,232,669 and 3,837,239.
Resonant systems are most useful in high power applications. The high power applied to the resonant system subjects it to large vibratory forces and displacement, as well as high velocity. In the past, it has been difficult to design node supports that can withstand such an environment. The conventional practice for determining the nodal positions of a resonant system is to apply a force impulse or a small vibrational force at the resonant frequency to its input and to observe the points of minimum vibration in the free ringing state of the resonant system. The resonant system is then held in place by node supports located at the determined points of minimum vibration so that the transfer of vibration energy to the frame is minimized.
Node support of prior resonant systems have proved less advantageous than desired because the node positions of the resonant systems, i.e., the points of minimum vibration, are frequency dependent. The free ringing nodes correspond precisely to the resonant frequency, i.e., the frequency at the peak of the resonant curve. But, for stable operation and to prevent overstressing of the resonant system, vibrations are conventionally applied thereto at a frequency of operation slightly below resonance, i.e., on the lower side of the peak of the resonant curve. As a result, in the conventional practice for determining the nodal positions the resonant system is not supported at its effective nodes for the actual frequency of operation, which subjects the node supports to violent vibrations.